实验10 Bezier曲线生成

#include <GL/glut.h>
#include <stdio.h>
#include <stdlib.h>
#include <vector>

using namespace std;

struct Point
{
	int x, y;
};

Point pt[4], bz[11];
vector<Point> vpt;
bool bDraw;
int nInput;

void CalcBZPoints()
{
	float a0,a1,a2,a3,b0,b1,b2,b3;
	a0=pt[0].x;
	a1=-3*pt[0].x+3*pt[1].x;
	a2=3*pt[0].x-6*pt[1].x+3*pt[2].x;
	a3=-pt[0].x+3*pt[1].x-3*pt[2].x+pt[3].x;
	b0=pt[0].y;
	b1=-3*pt[0].y+3*pt[1].y;
	b2=3*pt[0].y-6*pt[1].y+3*pt[2].y;
	b3=-pt[0].y+3*pt[1].y-3*pt[2].y+pt[3].y;

	float t = 0;
	float dt = 0.01;
	for(int i = 0; t<1.1; t+=0.1, i++)
	{
		bz[i].x = a0+a1*t+a2*t*t+a3*t*t*t;
		bz[i].y = b0+b1*t+b2*t*t+b3*t*t*t;
	}
}

void ControlPoint(vector<Point> vpt)
{
	glPointSize(2);
	for(int i=0; i<vpt.size(); i++)
	{
		glBegin (GL_POINTS);
		glColor3f (1.0f, 0.0f, 0.0f);   
glVertex2i (vpt[i].x,vpt[i].y);
		glEnd ();
	}
}

void PolylineGL(Point *pt, int num)
{
	glBegin (GL_LINE_STRIP);
	for(int i=0;i<num;i++)
	{		
		glColor3f (1.0f, 1.0f, 1.0f);   
		glVertex2i (pt[i].x,pt[i].y);		
	}
	glEnd ();
}

void myDisplay()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f (1.0f, 1.0f, 1.0f); 
	if (vpt.size() > 0)
	{
		ControlPoint(vpt);
	}

	if(bDraw)
	{
		PolylineGL(pt, 4);
		CalcBZPoints();
		PolylineGL(bz, 11);
	}

	glFlush();
}

void Init()
{
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_SMOOTH);

	printf("Please Click left button of mouse to input control point of Bezier Curve!\n");
}

void myReshape(int w, int h)
{
	glViewport(0, 0, (GLsizei) w,  (GLsizei) h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h);
}

void myMouse(int button, int state, int x, int y)
{
	switch (button)
	{
	case GLUT_LEFT_BUTTON:
		if (state == GLUT_DOWN) 
		{
			if (nInput == 0)
			{
				pt[0].x = x;
				pt[0].y = 480 - y;
				nInput = 1;
				vpt.clear();
				vpt.push_back(pt[0]);

				bDraw = false;
				glutPostRedisplay();
			}
			else if (nInput == 1) 
			{
				pt[1].x = x;
				pt[1].y = 480 - y;
				vpt.push_back(pt[1]);
				nInput = 2;
				glutPostRedisplay();
			}
			else if (nInput == 2) 
			{
				pt[2].x = x;
				pt[2].y = 480 - y;
				vpt.push_back(pt[2]);
				nInput = 3;
				glutPostRedisplay();
			}
			else if (nInput == 3) 
			{
				pt[3].x = x;
				pt[3].y = 480 - y;
				bDraw = true;
				vpt.push_back(pt[3]);
				nInput = 0;
				glutPostRedisplay();
			}
		}
		break;
	default:
		break;
	}
}

int main(int argc, char *argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(640, 480);
	glutCreateWindow("Hello World!");

	Init();
	glutDisplayFunc(myDisplay);
	glutReshapeFunc(myReshape);
	glutMouseFunc(myMouse);
	glutMainLoop();
	return 0;
}